Frank Pasquale follows a Joe Nocera article on credit scores with a great roundup of issues that the credit system imposes on American citizens, including arbitrariness, discriminatory effects and self-fulfilling prophecies. His article is worth a look even if you think you understand credit scores.
I’d like to add one more danger of credit scores: deceptive advertising. The way it works is that a bank advertises a great rate for those with “perfect credit.” What it doesn’t advertise is what the curve of credit scores versus rates looks like. There are two issues here. The first is that the market is inefficient, as figuring out what actual rates are often involves talking to a human, and usually disclosing enough personal information to make a fraudster drool. Inefficient markets favor the side with more information (the loan offerer) and lead to less trade than more transparent markets.
The second issue is that everyone is mislead by the headline rate. I’ve looked for data on what fraction of Americans are listed as having “perfect credit” or data on the distribution of interest rates people are really paying, and I’ve been unable to find it. For publicly traded companies, it’s sometimes possible to reverse engineer some of this, but not very much.